Interchangeable grounding outlet with non-rigid top



Sept. 15, 1964 P H. WINTER 3,148,927

INTERCHANGEABLE GROUNDING OUTLET WITH NON-RIGID TOP Filed Oct. 2, 1962 PAUL H. WINTER YMX M5 United States Patent 3,148,927 INTERCHANGEABLE GROUNDENG OUTLET WITH NON-RIGID T01? Paul H. Winter, Syracuse, N.Y., assignor to Pass & Seymour, Inc., Syracuse, N.Y., a corporation of New York Filed Oct. 2, 1962, Ser. No. 227,859 5 Claims. (Cl. 339-14) This invention relates to interchangeable grounding outlets and more particularly to such outlets having a nonrigid top and employing means for holding the contacts therein independent of engagement by such top.

It is a general object of the present invention to provide a novel and improved interchangeable grounding outlet having a top provided with plug blade ports closely adjacent its side walls and formed of a flexible material resistant to breaking under the strain of inserting or removing such blades.

More particularly it-isan object of the present invention to provide in an interchangeable grounding outlet means independent of the deformable and resilient top for holding the contact blade and terminal units in position without the need for fasteniugs extending into or through the walls or bottom of the insulating housing cup.

An important object of the present invention resides in the arrangement of the non-rigid top or cover for the insulating cup so that acceptable rigid insulation struts may be interposed between the tops of the terminal plates and the metal cover-retaining frame for maintaining the terminal-contact units in position against the bottom Wall of the insulation housing cup.

' Other and further objects and features of the present invention will be more apparent to those skilled in the art upon a consideration of the following specification and the accompanying drawing wherein is disclosed a single exemplary embodiment of the invention, with the understanding that such changes and modifications may be made therein as fall within the scope of the appended claims.

7 In said drawings:

FIGURE 1 is a top plan view of an interchangeable grounding outlet with non-rigid top constructed in accordance with the present invention;

FIGURE 2 is a vertical longitudinal section therethrough taken on line 2-2 of FIGURE 1; and

FIGURE 3 is a transverse, vertical section taken on line 33 of FIGURE 2.

Convenience outlets when used either singly or duplex in a single gang box and wall plate have a large enough standardized face on the disc exposed through the plate to accommodate both the main plug blades and a grounding plug prong without the openings for the blade and prong encroaching on the borders of the disc so that problems of breaking the disc edges adjacent the blade openings do not exist.

With the now standardized Despard Line interchangeable wiring devices, usable three to a single gang box and wall plate, the plate openings are fixed in size and shape. They will effectively accommodate the two blades of an attachment plug when they are spaced along the major axis of the disc exposed through a plate opening. However, wi-th the newer plugs having also a grounding prong arranged on an axis between and parallel to the blade faces the disc size requires the blades to be positioned with their long axes parallel to the straight sides of the disc and so close to them that the thin remaining wall is often cracked or broken away with careless use of a plug. The edge of the grounding prong on the long axis of the disc can be exposed through the wall of the disc without danger even if a metal wall plate is used, but this is not true of the plug blades because of their higher potentials.

The present invention contemplates use of a top or cover for an interchangeable outlet of the grounding prong type which is made from a suitable non-rigid plas tic, such as one of the more common thermo-plastics, which is sufficiently resistant to cracking or breaking to be effective under the most drastic usage. Such plastics are unacceptable to the Underwriters Laboratories for the support of current carrying parts, because they cannot pass the rigid combustibility tests. They, therefore, cannot be used for supporting, positioning or other direct engagement with current carrying parts of a wiring device since their lack of fire resistance will make it easier for current carrying parts to move out of position and thereby add hazards of short circuits, etc. The physical properties of such therrno-plastics are so satisfactory, however, for solving the breakage problems noted above that their use is highly desirable in spite of their drawbacks.

Reference should now be had to the drawing for an understanding of the solution to the problem. It illustrates an interchangeable grounding outlet of the Despard Line type such as shown in the patent to Paul H. Winter, No. 2,872,503, granted February 3, 1959, with, however, those modifications necessary to adapt it to a thermo-plastic top or cover.

The present invention differs in construction from that illustrated in the Winter patent by providing the main body shell 19 of the convenience outlet as a molded unit formed from a suitable thermo-setting plastic in the form of an open top closed bottom cup having a separate closure top or cover 111, as contrasted with the patented structure in which the cover is integral with the cup and the closure comprises a separable bottom plate.

The cup or body portion 10 of the housing, seen in FIG- -URES 2 and 3, is divided transversely by wall 12 extending upwardly from the integral bottom 13 and secured thereto and to the side walls 14. This separates a compartment 16, shown at the left in FIGURE 2, which contains the combined terminal plate 17 and contact spring 18 for the grounding prong, not shown, which is introduced through the aperture 20 in the cover substantially as shown in the patent. The upper end of the terminal plate 17 is narrowed into a strap turned over at right angles to provide a tang as shown at 21 to overlie the upper edge of end wall 22 of the cup. The lower edge of terminal plate 17 rests on the bottom wall of the cup and the lateral edges are received in grooves, not shown, in the side walls of the cup. The usual screw 23 for attaching a grounding conductor, if required, to the terminal plate is illustrated and extends through an appropriate aperture in end wall 22.

The space to the right of partition 12 is divided into two transversely disposed compartments by the center partition wall 25, FIGURE 3, which is integrated with wall 12 and the bottom 13 during the molding operation. One of the thus formed compartments is illustrated at 26 in FIGURE 2 and like its companion receives an integral terminal plate and contact arrangement comprising a flat bottom plate 27 resting on cup bottom 13 and having upturned integral terminal plate 28, fitted with a terminal screw 29 which is exposed through end wall 30 of the cup. The terminal plate above the screw engages end wall 30 for a short distance above the screw head opening as seen at 31, and the left edge of the fiat bottom plate 27 substantially engages the center partition 12. From the sides of plate 27 are turned up contact members 32, parallel to each other and spaced apart except where their curved ends 33 are bent toward each other and then provided with the outward flaring ends 34 to guide one of the main blades of an attachment plug between them, in the conventional manner.

The cover plate 1 1 for closing the top of the cup 10 is molded from a suitable thermoplastic or other material which has suificient resilience or elasticity so that the of 20 makes no difference.

very thin edges 36, seen in FIGURES l and 3, beside the ports 37 for'the main prongs of an attachment plug are resistant to cracking or breaking due to tilting or misalignment Of the plug during insertion or removal. Ports 37 and port Ztl for the grounding prong extend through the raised disc or neck 3?, which passes through an aper ture in the usual wall plate. Sincethe prong received in opening Ztl is at ground potential as are adjacent metal parts and terminal plate 17 and contact 13, the open side Below the raised disc-like portion 39, the cover it spreads both laterally and longitudinally, to the width of the cup as seen at 4th in FIGURE 3, but not to its length, the flat portion for. closure of the cup terminating at 41 at the right and at 42 on the left as seen in FIGURE 2, just inside of the end walls 30 and 22 respectively, which are higher than the side walls 14 by the thickness of the cover. The cover, therefore, rests-on the edges 46 of the side walls 14 as clearly seen in FIG- URE 3. to tang 21. The right edge is spaced from end wall 359 by the thickness of terminal plate 28 to accommodate the pair of holddowns 46 comprising fire resistant insulation plates of rectangular shape whose lower edges bear on the upper edges of terminal plates 28, as seen in FiG- URES 2 and 3 and whose upper edges extend to the height of end wall 30;

The cover is held in position and secured to the body portion of the housing by means of the metal frame Sti comprising a flat plate of sheet metal perforated to pass over not only the raised neck section 39 of the top or cover but also the larger rectangular portion 51 thereof Its left edge is notched for the strap leading,

which provides areas to bear against the under surface of a mounting strap in which the device is secured. This cover plate is provided with downturned end straps 54,

which engage the end walls of the cup and'are bent under protuberances 55 thereon at each end to hold the assembly together. Irnmediately beneath the cover plate is the thin metal sheet 58 having the integral extension or tab 59 which is sized to extend beneath the end of the a mounting strap for the outlet and is pressed into engagement with the wall box tab by the mounting screw for the strap, all as shown in the patent.

FIGURES 2 and 3 clearly illustrate how the upper edges of the hold-down plates 46 engage directly beneath the metal sheet 58 and the overlying flat portion 5% of the metal cover plate and secure the main terminal plates 28 and their integral plug blade contacts in their respective compartments 26, thereby wholly relieving the thermo-plastic cover plate from this duty and insuring the terminals remaining in proper position inspite of an melting or burning of the top.

. In alike manner the other end of the sheet 58 and cover plate 50 rest directly on the tang 21 of terminal plate 17 for the grounding contact spring. Tab 59 of sheet 58 being in engagement with the mounting strap and wall box insures that the spring 18 which engages the grounding prong of the plug is properly grounded, if the box is at ground potential. it further grounding is required, because the box is not adequately grounded, a conductor under the head of screw 23 will take care of the problem.

Thus, the new form of outlet provides for a thermoplastic top to prevent cracking or breaking of the thin walls, and yet secures the main term-inalsand contacts and I the grounding terminal in position without resort to engagement by this thermo-plastic part as objected to by the Underwriters. I i

I claim:

1. An interchangeable grounding outlet having a protruding neck with'a face size requiring main plug blade ac cess openings parallel and so close to the flat sides of the neck as to leave only thin adjacent walls, an insulating body shell of rectangular cup-shape having side and end walls, open at the front and closed by a bottom wall, main contacts and a grounding contact in said shell, each of said side walls, fitting between said end walls andbeing formed of a thermoplastic material giving resilience to said thin walls bordering said openings, a, metal frame perforated to pass over said neck, and rest on said cover adjacent the neck, means securing the frame to the body shell and a thin plate of fire resistant insulating material type extending from the top of each terminal plate alongside the adjacent end Wall of said cup and positioned by said frame to hold said terminal plate and its. contact rigidly in position in the cup.

2. in a grounding outlet of the interchangeable type in combination; a cup like body shell, rectangular in plan, of thermo-setting plastic having a bottom Wall and integral side, end and internal partition walls forming compartments therein; main contacts in side-byside cornpartments adjacent one end wall each having a bottom plate against said bottonrwall and an upturned terminal plate extending upwardly along said end wall; saidend wall being higher than said side and partition walls; a cover plate for the open face of said shell bearing on the upper edges of said sidewalls, fitting between the higher end walls and having a protruding. neck provided with access openings leading to said compartments and contacts, two of said openings being so close to flat sides of .said neck as to'leave only thin intervening walls; said cover plate being formed of a flexible plastic to prevent cracking of said thin walls; a flat metal frame surrounding said neck, overlying the cover plate and the tops of said end walls and secured to said body shell to hold the cover assembled thereto; and an insulatingplate of fire resistant insulating material extending between the under face of said metal frame and the upper end of each terend wall, a'tang extending upwardly from said grounding contact along said other end wall and over its upper edge for engagement by the under face of said thin sheet, said tang being engaged by the other end wall oi said cover plate to hold against the cup end wall.

5; A grounding outlet of the interchangeable type in combination; an insulating cup having a closed'bottom, side walls and higher end walls; a cover .plate of thermoplastic resting on said side walls and fitting between said end walls; a neck protruding from said plate'and having flat side walls; plug prong ports in said neck, one parallel to and near each side wall; a compartment in said cup beneath each said port; a combined contact and terminal plate in each compartment having a bottom plate resting on the cup bottom and an integral terminal plate against an end wall of the cup; a fire resistant, rigid insulation strip bearing on the top edge'of said terminal plate and extending between said end wall and the adjacent end of said cover; and a metal plate secured to the cup body and having a portion holding the cover in position and a portion pressing said insulation strip down onto said terminal plate. 1

References tCited in'the file of this patent UNITED STATES PATENTS McC-loy et al. .p Oct. 30,1934 2,869,102

2,872,503 Winter Q. Feb. 3, 1959 Hubbell Jan. 13, 1959 

5. A GROUNDING OUTLET OF THE INTERCHANGEABLE TYPE IN COMBINATION; AN INSULATING CUP HAVING A CLOSED BOTTOM, SIDE WALLS AND HIGHER END WALLS; A COVER PLATE OF THERMOPLASTIC RESTING ON SAID SIDE WALLS AND FITTING BETWEEN SAID END WALLS; A NECK PROTRUDING FROM SAID PLATE AND HAVING FLAT SIDE WALLS; PLUG PRONG PORTS IN SAID NECK, ONE PARALLEL TO AND NEAR EACH SIDE WALL; A COMPARTMENT IN SAID CUP BENEATH EACH SAID PORT; A COMBINED CONTACT AND TERMINAL PLATE IN EACH COMPARTMENT HAVING A BOTTOM PLATE RESTING ON THE CUP BOTTOM AND AN INTEGRAL TERMINAL PLATE AGAINST AN END WALL OF THE CUP; A FIRE RESISTANT, RIGID INSULATION STRIP BEARING ON THE TOP EDGE OF SAID TERMINAL PLATE AND EXTENDING BETWEEN SAID END WALL AND THE ADJACENT END OF SAID COVER; AND A METAL PLATE SECURED TO THE CUP BODY AND HAVING A PORTION HOLDING THE COVER IN POSITION AND A PORTION PRESSING SAID INSULATION STRIP DOWN ONTO SAID TERMINAL PLATE. 